Hypnosis is an environment of the mind where unconscious learnings that you have acquired over a lifetime become suddenly available. In hypnosis you are in a heightened state of awareness. You are less critical in this state.  You are ready to  learn new patterns at the subconscious level which could help you make positive changes in your life, or alter old learnings which do not serve you in a positive way. Hypnosis is not sleep, you hear everything that is being said by the hypnotist. Hypnosis is holistic and has no side effects. You are more suggestible to new ideas and learnings in the hypnotic state.  However, you maintain full control and can emerge from hypnosis at anytime you choose. You cannot get stuck in hypnosis indefinitely. If left unattended, after a few minutes you will automatically emerge from hypnosis.
Everyone has experienced some form of hypnosis while Driving or Watching TV when you were so engrossed and focussed that you lost track of time and was not concerned of the happenings around you.